1. Field of the Invention
This invention generally relates to an energy efficient fractionation method for the separation of two close boiling point components from a multi-component mixture. The process is particularly applicable to the separation of isobutane and normal butane from a depropanized gasoline feed stream, resulting in energy savings of approximately 50% over conventional methods.
2. Description of the Prior Art
Many refinery and petrochemical processes require relatively pure quantities of various isomers of a single homologous hydrocarbon series as raw materials. These substances are commonly found mixed with a myriad of other substances in natural gas and crude oil sources. Problems arise however in industrial separation of the isomers due to the closeness in isomer boiling points. This closeness in boiling points and volatility usually requires a large number of equilibrium contacting stages in the fractionating equipment in addition to the use of high reflux ratios to effect the desired separation and product quality. The higher the reflux ratio required, the more energy is necessary for reboiling and condensing the internal tower streams. This increased energy has as a necessary correlary, larger auxiliary equipment to facilitate the greater energy transfer.
It is therefore an object of this invention to provide an energy efficient fractionation process for the separation of two close boiling point components in a multi-component system, which may be easily and economically incorporated into existing designs.